1. Field of the Invention
This invention relates to a method of controlling an automatic sheet connecting and feeding apparatus in which folded sheets are successively connected to each other.
2. Background
U.S. Pat. application Ser. No. 184,917 discloses an apparatus in which folded sheets, each of which is folded zigzag in the form of a stack of sheets are successively conveyed with conveying means, and are connected to one another during conveyance, so as to be fed to a processing device. In Japan, the apparatus has been laid open to public inspection under Japanese Patent Application Nos. 88675/1987, 88766/1987 and 88767/1987 (the term "OPI" as used herein means an "unexamined published application"). Such an apparatus is disclosed in Japanese Patent Application No. 145058/1986.
The difficulties associated with such an apparatus are as follows. When the top sheet of a folded sheet is lifted by suction and retained by a suction and retaining means and is positioned so as to be connected to the bottom sheet of the preceding folded sheet the elasticity of the sheet causes the top sheet to become detached from the suctioning and retaining means that is, it is difficult for the suctioning and retaining means to positively suction and retain the top sheet. Sometimes, the suction and retaining means may suction and retain more than one sheet.
Furthermore, in order to position the top and bottom sheets for connecting them to each other, positioning pins are inserted into positioning holes. However, since the folded sheets are heavy the sheets may not be properly positioned, and the positioning holes may be broken.
The conventional apparatus has no means for detecting whether or not the sheet have been satisfactorily connected to each other. Therefore, the sheets are often disconnected from each other, with the result that the feeding of folded sheets to the following processing device is suspended, and accordingly the device must be stopped.
Further, the sheets of the folded sheet on the last conveyor are fed to the processing device at high speed. Therefore, if the number of sheets remaining on the last conveyor becomes small, the folded sheet on the last conveyor is pulled in a direction opposite to the sheet forwarding direction against the frictional resistance between the folded sheet and the conveyor. In this case, a sheet detecting means at the last stage determines that no folded sheet is available on the last conveyor, and operates to move the folded sheet on the preceding conveyor to the last conveyor, as a result of which the sheets remaining on the last conveyor are caught between the folded sheet thus moved and the apparatus frame; that is, the feeding of the sheets to the processing device is suspended.